1. Field of the Invention
This invention relates to a cutter having a retractable blade supported on one end of a shank which is axially movable in a holder.
2. Description of the Prior Art
The most basic form of a cutter has a naked blade attached to one end of a handle. The naked blade is dangerous when the cutter is not used. This is particularly the case when the cutter is carried about. The naked blade also has the disadvantage of being easily damaged.
There is known a cutter having a vinyl tube or similar cover which can be placed over a blade. The cover is, however, very likely to be broken by the blade. It is also very likely that the cover may be lost.
These problems can be solved by a cutter having a retractable blade. This cutter has a part which can be pressed or turned to push out the blade or draw it back. The blade is actuated by a mechanism which is similar to that employed by a mechanical pencil or a ballpoint pen for moving its lead or ball. The blade requires a sufficiently strong support for withstanding the force to which it is subjected when the cutter is used. The blade support is usually a molded product of a synthetic resin. One end of the blade is fixed in the molded support and the blade is movable out of, or back into, a holder when a push-button is pressed. The blade and its support form a unitary assembly which has to be changed completely when it is necessary to change the blade. The replacement of the blade is, therefore, expensive. Moreover, it is necessary to remove a cap from the tip of the holder when changing the blade.